Exegesis:

egeneto de … eiselthein auton eis tēn sunagōgēn kai didaskein ‘and it happened that he went into the synagogue (aorist, punctiliar event) and taught (present, linear event).’ Cf. on 6.1 and 1.8.

kai en anthrōpos ekei kai hē cheir autou hē dexia ēn xēra ‘and there was a man there and his right hand was withered.’ Co-ordination of two clauses where subordination would be normal in Greek. The emphasis is on the second clause.

xēros ‘dry,’ of wood in 23.31, ‘withered,’ i.e. incapable of motion. In view of ekteinon tēn cheira sou ‘stretched out your hand’ (v. 10) xēros is best understood as referring to paralysis.

Translation:

The introductory statement about time and place is often better rendered as an independent sentence.

A man was there, or, ‘there happened to be a man there, or, in the congregation’ (cf. New English Bible).

Whose right hand was withered, or, ‘who had a withered right hand, or, a right hand that was withered.’ For withered the rendering should imply the impossibility to stretch out the hand, or arm, and the paralysis meant is a non-congenital ailment (cf. on v. 10).

Quoted with permission from Reiling, J. and Swellengrebel, J.L. A Handbook on the Gospel of Luke. (UBS Handbook Series). New York: UBS, 1971. For this and other handbooks for translators see here . Make sure to also consult the Handbook on the Gospel of Mark for parallel or similar verses.