Intending to monitor bar area (5)
I believe the answer is:
gonna
'intending to' is the definition.
(I've seen this in another clue)
'monitor bar area' is the wordplay.
'monitor' becomes 'goanna' (type of monitor lizard).
'bar' indicates named letters should be taken away ('bar' can mean 'except' or 'apart from').
'area' becomes 'a' (maths abbreviation).
'goanna' with 'a' taken away is 'GONNA'.
(Other definitions for gonna that I've seen before include "Going to (informal)" , "Informally, about to get" , "- - Build A Mountain (song)" , "Shortly intending to" .)