Intended to be a nasty team leader (5)
I believe the answer is:
meant
'intended' is the definition.
(to mean something is to intend it)
'a nasty team leader' is the wordplay.
'a nasty' becomes 'mean' (I've seen this before).
'leader' indicates taking the first letters.
The initial letter of 'team' is 't'.
'mean'+'t'='MEANT'
'to be' is the link.
(Other definitions for meant that I've seen before include "Denoted" , "Signified" , "planned" , "designed" , "proposed" .)