Understand notice Poles brought in (5)
I believe the answer is:
sense
'understand' is the definition.
(thesaurus)
'notice poles brought in' is the wordplay.
'notice' becomes 'see' (I've seen this before).
'poles' becomes 'ns' (North and South poles).
'brought in' is an insertion indicator.
'see' placed around 'ns' is 'SENSE'.
(Other definitions for sense that I've seen before include "Practicality, often common (5)" , "Pick up point" , "Tenor" , "smell, for example" , "Sound practical judgment" .)