Assume tea fork bent, admittedly (4,3,7)
I believe the answer is:
take for granted
'assume' is the definition.
(taking for granted is a kind of assuming)
'tea fork bent admittedly' is the wordplay.
'bent' is an anagram indicator.
'admittedly' becomes 'granted' (I've seen this before).
'tea'+'fork'='teafork'
'teafork' is an anagram of 'takefor'.
'takefor'+'granted'='TAKE FOR GRANTED'
(Other definitions for take for granted that I've seen before include "Treat casually and without respect" , "Assume" .)