I sped round lake to drive away (6)
I believe the answer is:
dispel
'drive away' is the definition.
('dispel' can be a synonym of 'drive away')
'i sped round lake' is the wordplay.
'round' is an anagram indicator.
'lake' becomes 'l'.
'i'+'sped'='isped'
'isped' is an anagram of 'dispe'.
'dispe'+'l'='DISPEL'
'to' acts as a link.
(Other definitions for dispel that I've seen before include "Drive away and scatter" , "Make (something) disappear" , "Lisped (anag)" , "Make (feeling) disappear" , "Dissipate or drive off" .)