Dance band's leader entering strange area (5)
I believe the answer is:
rumba
'dance' is the definition.
(rumba is a kind of dance)
'band's leader entering strange area' is the wordplay.
'leader' indicates taking the first letters.
'entering' indicates putting letters inside.
'strange' becomes 'rum' (I've seen this before).
'area' becomes 'a' (maths abbreviation).
The initial letter of 'bands' is 'b'.
'rum'+'a'='ruma'
'b' going within 'ruma' is 'RUMBA'.
(Other definitions for rumba that I've seen before include "Caribbean dance" , "one's on the floor for it" , "Strictly round" , "Cuban folk-dance" , "number of steps" .)