Secures site poorly (4)
I believe the answer is:
ties
'secures' is the definition.
(tying is a kind of securing)
'site poorly' is the wordplay.
'poorly' is an anagram indicator.
'site' anagrammed gives 'TIES'.
(Other definitions for ties that I've seen before include "Connects" , "Attaches, knots" , "obligations" , "Links" , "Fastens with a knot" .)