Sadly forget North-West must find great support (5,2,8)
I believe the answer is:
tower of strength
'great support' is the definition.
(I've seen this before)
'sadly forget north-west' is the wordplay.
'sadly' is an anagram indicator.
'forget'+'north'+'west'='forgetnorthwest'
'forgetnorthwest' anagrammed gives 'TOWER OF STRENGTH'.
'must find' acts as a link.
(Other definitions for tower of strength that I've seen before include "True supporter" , "One's extremely dependable when needed" , "powerful tug?" , "One very reliable" , "Person giving support" .)