Go off to climb, finding rocky height (3)
I believe the answer is:
tor
'rocky height' is the definition.
(I've seen this in another clue)
'go off to climb' is the wordplay.
'go off' becomes 'rot' (as in food going off).
'to climb' says the letters should be written in reverse (I've seen 'climbs' mean this).
'rot' written backwards gives 'TOR'.
'finding' is the link.
(Other definitions for tor that I've seen before include "(Dartmoor) rocky hill" , "A rocky hill in Devon" , "Rot on a peak in Devon" , "feature of Glastonbury" , "fell" .)