Bat I'm using to get boundary (5)
I believe the answer is:
ambit
'boundary' is the definition.
(I've seen this in another clue)
'bat i'm using' is the wordplay.
'using' is an anagram indicator (the letters used in a different way).
'bat'+'im'='batim'
'batim' anagrammed gives 'AMBIT'.
'to get' acts as a link.
(Other definitions for ambit that I've seen before include "Range, scope" , "Circuit, compass" , "Scope or confines" , "round" , "Range - surroundings" .)