Natural aptitude may be present (4)
I believe the answer is:
gift
This could be a double definition.
'natural aptitude' is the first definition.
'gift' can be an answer for 'aptitude' (gift is a kind of aptitude). I'm not sure about the 'natural' bit.
'be present' is the second definition.
(I've seen this before)
'may' is the link.
Can you help me to learn more?
(Other definitions for gift that I've seen before include "''Never look a .... horse in the mouth" , "Endowment" , "Natural talent" , "flair" , "Present or special talent" .)