Still periodically spying, study process in plant (14)
I believe the answer is:
photosynthesis
'process in plant' is the definition.
'photosynthesis' can be an answer for 'process' (photosynthesis is a kind of process). I'm unsure of the 'in plant' bit.
'still periodically spying study' is the wordplay.
I cannot really understand how this works, but
'still' could be 'photo' (I've seen this before) and 'photo' is located in the answer.
The remaining letters 'synthesis' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for photosynthesis that I've seen before include "plant activity" , "plant process" , "what plants can do" .)