Ape mother's complicated mood (10)
I believe the answer is:
atmosphere
'mood' is the definition.
(atmosphere is a kind of mood)
'ape mother's complicated' is the wordplay.
'complicated' indicates anagramming the letters (a complex or confusing ordering of the letters).
'ape'+'mothers'='apemothers'
'apemothers' is an anagram of 'ATMOSPHERE'.
(Other definitions for atmosphere that I've seen before include "prevailing mood" , "Feeling" , "character" , "climate" , "Spirit" .)