Peseta we changed for a climber (5,3)
I believe the answer is:
'climber' is the definition.
(I've seen this before)
'peseta we changed' is the wordplay.
'changed' indicates anagramming the letters.
'pesetawe' with letters rearranged gives 'SWEET PEA'.
'for a' acts as a link.
(Other definitions for sweet pea that I've seen before include "Eat, weeps and gets climbing flowers" , "flowering plant" , "Garden plant with brightly coloured flowers" , "Garden plant with pastel-coloured flowers" , "Climbing plant with pastel-coloured flowers" .)