Dig garden’s first exposed borders (5)
I believe the answer is:
nudge
'dig' is the definition.
(thesaurus)
'garden's first exposed borders' is the wordplay.
'first' says to take the initial letters.
'exposed' becomes 'nude' (I've seen this before).
'borders' means one lot of letters goes inside another.
The initial letter of 'gardens' is 'g'.
'g' inserted into 'nude' is 'NUDGE'.
(Other definitions for nudge that I've seen before include "Dig with elbow" , "Push gently" , "Give a reminder" , "Light touch or push" , "suggestive move" .)