Crawled (4,2,3,5)
I think it could be either:
went on all fours
'crawled' is the definition.
('creep' can be a synonym of 'crawl')
This is the entire clue.
(Other definitions for crept that I've seen before include "was obsequious" , "Moved slowly with stealth and caution" , "Moved stealthily" , "cringed" , "Sneaked" .)