Male beast and one female in mountainous plateau (6)
I believe the answer is:
massif
'mountainous plateau' is the definition.
(I've seen this before)
'male beast and one female' is the wordplay.
'male' becomes 'm' (common abbreviation).
'beast' becomes 'ass' (I've seen this before**).
'and' means one lot of letters go next to another.
'one' becomes 'i' (Roman numeral).
'female' becomes 'f' (abbreviation).
'm'+'ass'+'i'+'f'='MASSIF'
'in' is the link.
(Other definitions for massif that I've seen before include "High points" , "IMF ass found on mountainous plateau" , "Central mountain mass" , "Geological mountain formation" , "mountain peak" .)