Concentrate on providing a great range (6)
I believe the answer is:
massif
'a great range' is the definition.
'massif' can be an answer for 'range' (I've seen this before). I'm unsure of the 'a great' bit.
'concentrate on providing' is the wordplay.
'concentrate' becomes 'mass' (I've seen this in another clue).
'on' says to put letters next to each other (in a down clue, letters appear on others).
'providing' becomes 'if' (eg 'providing it's sunny' means 'if it's sunny').
'mass'+'if'='MASSIF'
Can you help me to learn more?
(Other definitions for massif that I've seen before include "Compact mountainous area" , "IMF ass found on mountainous plateau" , "Mountain centre" , "Compact grouping of mountains" , "huge piece of crust" .)