Person almost ruined reproductive body (5)
I believe the answer is:
spore
'reproductive body' is the definition.
(I've seen this before)
'person almost ruined' is the wordplay.
'almost' means to remove the last letter (most of the word but not all of it).
'ruined' indicates an anagram.
'person' with its last letter taken off is 'perso'.
'perso' is an anagram of 'SPORE'.
(Other definitions for spore that I've seen before include "Reproductive body produced by fungi" , "Tiny reproductive cell of fungus or fern" , "Fungus reproducer" , "Fungal cell" , "Ropes (anag.)" .)