Stirring loam pit is most favourable (7)
I believe the answer is:
optimal
'most favourable' is the definition.
(I've seen this before)
'stirring loam pit' is the wordplay.
'stirring' indicates anagramming the letters.
'loam'+'pit'='loampit'
'loampit' anagrammed gives 'OPTIMAL'.
'is' is the link.
(Other definitions for optimal that I've seen before include "Best or most favourable" , "Am pilot being at best" , "couldn't be better" , "Best possible" , "Plot aim (anag) - most favourable" .)