Stroke head of cat on green overlooking lake (5)
I believe the answer is:
crawl
'stroke' is the definition.
(crawl is a kind of stroke)
'head of cat on green overlooking lake' is the wordplay.
'head of' suggests taking the first letters.
'on' means one lot of letters go next to another.
'green' becomes 'raw' ('raw' can be a synonym of 'green'**).
'overlooking' means one lot of letters go next to another (down clues only).
'lake' becomes 'l'.
The first letter of 'cat' is 'c'.
'c'+'raw'+'l'='CRAWL'
(Other definitions for crawl that I've seen before include "Go on hands and knees" , "Baby-like advance" , "This can take you quickly through water" , "fawn" , "Scramble on all fours" .)