Complaint of menial working on top of tower (7)
I believe the answer is:
ailment
'complaint' is the definition.
('ailment' can be a synonym of 'complaint')
'menial working on top of tower' is the wordplay.
'working' is an anagram indicator.
'on top of' indicates taking the first letters (I've seen 'on top' mean this).
The first letter of 'tower' is 't'.
'menial' with letters rearranged gives 'ailmen'.
'ailmen'+'t'='AILMENT'
'of' is the link.
(Other definitions for ailment that I've seen before include "Sickness" , "Slight but persistent illness" , "Minor illness" , "I lament (anag.)" , "Physical disorder" .)