Climber putting back a spike (5)
I believe the answer is:
liana
'climber' is the definition.
(climbing plant)
'back a spike' is the wordplay.
'back' says the letters should be written backwards.
'spike' becomes 'nail' (I've seen this before).
'a'+'nail'='anail'
'anail' written backwards gives 'LIANA'.
'putting' acts as a link.
(Other definitions for liana that I've seen before include "Climbing plant of rainforests" , "Woody climbing tropical plant -- a nail (anag)" , "Woody climbing (usually tropical) plant" , "Rainforest climber" , "Tropical forest climber" .)