We gather catchword wears thin (5)
I believe the answer is:
frays
'wears thin' is the definition.
'we gather catchword' is the wordplay.
'we gather' indicates a 'sounds like' (homophone) clue (gather can mean to hear).
'catchword' becomes 'phrase' (I've seen this in another clue).
'phrase' is a homophone of 'FRAYS'.
(Other definitions for frays that I've seen before include "Shows effect of strain" , "Becomes worn; skirmishes" , "fights" , "Strains one's nerves" , "gets worn out" .)