Couple in plant put right (8)
I believe the answer is:
repaired
'put right' is the definition.
'couple in plant' is the wordplay.
'couple' becomes 'pair' (synonyms).
'in' indicates putting letters inside.
'plant' becomes 'reed' (reed is a kind of plant).
'pair' inserted within 'reed' is 'REPAIRED'.
(Other definitions for repaired that I've seen before include "Mended, restored" , "Restored to good condition" , "Fixed" , "Put right - went" , "Retired" .)