Inclined to run, when given lead (6)
I believe the answer is:
aslope
'inclined' is the definition.
(similar in meaning)
'run when given lead' is the wordplay.
'run' becomes 'lope' (lope is a kind of run).
'when' becomes 'as' (eg 'when I walked' means 'as I walked').
'given lead' means one lot of letters go next to another (some letters lead or go in front of others).
'lope' put after 'as' is 'ASLOPE'.
'to' is the link.
(Other definitions for aslope that I've seen before include "Leaning" , "Not flat" , "Inclined" , "italic" , "not on the level" .)