Very long time to accept Scottish mountain plant (7)
I believe the answer is:
verbena
'plant' is the definition.
(verbena is a kind of plant)
'very long time to accept scottish mountain' is the wordplay.
'very' becomes 'v' (common abbreviation).
'long time' becomes 'era' (a long period of time).
'to accept' is an insertion indicator.
'scottish mountain' becomes 'ben' (Scottish term for a peak, eg Ben Nevis).
'era' going around 'ben' is 'erbena'.
'v'+'erbena'='VERBENA'
(Other definitions for verbena that I've seen before include "Vervain (plant)" , "Ornamental plant with showy flowers" , "Ornamental pant" , "Garden plant" , "Herbaceous plant" .)