Frame of mind almost low (3)
I believe the answer is:
moo
'low' is the definition.
(both can mean to make the noise of a cow)
'frame of mind almost' is the wordplay.
'frame of mind' becomes 'mood' (I've seen this before).
'almost' means to remove the last letter (most of the word but not all of it).
'mood' with its last letter removed is 'MOO'.
(Other definitions for moo that I've seen before include "Cow's sound" , "Cow's call" , "Guernsey noise?" , "Bovine low" , "Low (of cattle)" .)