Hard bugger climbing for money (4)
I believe the answer is:
dosh
'for money' is the definition.
(slang term)
'hard bugger climbing' is the wordplay.
'hard' becomes 'h' (abbreviation used in pencil classifications).
'bugger' becomes 'sod'.
'climbing' says the letters should be written backwards (in a down clue, letters climb up).
'h'+'sod'='hsod'
'hsod' reversed gives 'DOSH'.
(Other definitions for dosh that I've seen before include "Lolly (slang)" , "Money (slang)" , "Money (sl.)" , "currency" , "Bread - gravy - dough" .)