Fat to be seared in part (5)
I believe the answer is:
obese
'fat' is the definition.
('obese' can be similar in meaning to 'fat')
'to be seared in part' is the wordplay.
'in part' says the answer is hidden in the clue.
'OBESE' is hidden within 'to be seared'.
(Other definitions for obese that I've seen before include "in need of slimming down" , "More than podgy" , "Enormous" , "carrying remarkable weight" , "Excessively fat" .)