Physical training to keep climber mostly flexible? (6)
I believe the answer is:
pliant
'flexible?' is the definition.
(I know that elastic can be written as pliant)
'physical training to keep climber mostly' is the wordplay.
'physical training' becomes 'PT' (Physical Training).
'to keep' indicates putting letters inside.
'climber' becomes 'liana' (climbing plant).
'mostly' means to remove the last letter.
'liana' with its last letter taken off is 'lian'.
'pt' going around 'lian' is 'PLIANT'.
(Other definitions for pliant that I've seen before include "docile" , "Bendable" , "Bending easily" , "Tractable" , "Supple or flexible" .)