What leisurely walker did -- risked going topless (6)
I believe the answer is:
ambled
'what leisurely walker did' is the definition.
(to amble is to go for a leisurely walk)
'risked going topless' is the wordplay.
'risked' becomes 'gambled' ('gamble' can be a synonym of 'risk').
'going topless' means to remove the first letter.
'gambled' with its first letter taken off is 'AMBLED'.
(Other definitions for ambled that I've seen before include "Sauntered" , "Walked casually" , "Walked slowly - blamed for it" , "'Walked leisurely, moseyed (6)'" , "Walked lazily along - so blamed" .)