Fat hidden by robe, seemingly (5)
I believe the answer is:
obese
'fat' is the definition.
(similar in meaning)
'hidden by robe seemingly' is the wordplay.
'hidden' indicates the answer is hidden within the clue.
'OBESE' is hidden within 'by robe seemingly'.
(Other definitions for obese that I've seen before include "Grossly fat" , "Morbidly fat" , "having generous corporation" , "Having excessive girth" , "in need of slimming down" .)