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