Person cherished a large flower section (5)
I believe the answer is:
petal
'flower section' is the definition.
'petal' can be an answer for 'flower' (thesaurus). I'm not certain of the 'section' bit.
'person cherished a large' is the wordplay.
I cannot really understand how this works, but
'person' could be 'pet' (pet is a kind of person) and 'pet' is present in the answer.
'a' is found in the answer.
'large' could be 'l' (eg in clothes sizes) and 'l' is found within the answer.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for petal that I've seen before include "part of seven [VIOLA]" , "Corolla leaf" , "Plate (anag.)" , "Colourful flower part" , "Brightly-coloured part of flower" .)