Wife needs gag - poor fellow! (6)
I believe the answer is:
wretch
'poor fellow' is the definition.
'wretch' can be an answer for 'fellow' (I have seen 'Miserable fellow' mean 'wretch' so perhaps 'fellow' could also mean 'wretch'). I am unsure of the 'poor' bit.
'wife needs gag' is the wordplay.
'wife' becomes 'w'.
'needs' means one lot of letters go next to another.
'gag' becomes 'retch' (I've seen this before).
'w'+'retch'='WRETCH'
Can you help me to learn more?
(Other definitions for wretch that I've seen before include "Good-for-nothing" , "Person in pitiful circumstances" , "Disreputable person" , "Scoundrel" , "Swine" .)