Nosy chap foolishly brought back an obsequious one (9)
I believe the answer is:
sycophant
'an obsequious one' is the definition.
(I've seen this before)
'nosy chap foolishly brought back' is the wordplay.
'foolishly' indicates anagramming the letters.
'back' suggests the final letters.
The final letter of 'brought' is 't'.
'nosy'+'chap'='nosychap'
'nosychap' anagrammed gives 'sycophan'.
'sycophan'+'t'='SYCOPHANT'
(Other definitions for sycophant that I've seen before include "obsequious one" , "yes-man" , "old informer" , "receiving ultimate in flattery from one such?" , "Uriah Heep, say" .)