Fawn starts to cautiously run along wooded lane (5)
I believe the answer is:
crawl
'fawn' is the definition.
('crawl' can be a synonym of 'fawn')
'starts to cautiously run along wooded lane' is the wordplay.
'starts to' suggests taking the first letters.
The initial letters of 'cautiously run along wooded lane' is 'CRAWL'.
(Other definitions for crawl that I've seen before include "Creep or move slowly" , "something used at the pool" , "Go slow" , "Move slowly (as a baby does?)" , "be overrun" .)