Rounded projection in theatre initially absent (4)
I believe the answer is:
lobe
'rounded projection' is the definition.
(I've seen this in another clue)
'theatre initially absent' is the wordplay.
'theatre' becomes 'globe' (I've seen this before).
'initially absent' means to remove the first letter.
'globe' with its initial letter taken away is 'LOBE'.
'in' acts as a link.
(Other definitions for lobe that I've seen before include "flap" , "Rounded projection of a larger structure" , "Base of ear" , "part of brain" , "could be site of a 24 [STUD]" .)