Sources of strength in the west and south (5)
I believe the answer is:
thews
'sources of strength' is the definition.
I don't know anything about this answer so I cannot judge whether this works.
'the west and south' is the wordplay.
'west' becomes 'W' (abbreviation).
'and' says to put letters next to each other.
'south' becomes 's' (abbreviation).
'the'+'w'+'s'='THEWS'
'in' acts as a link.
Can you help me to learn more?
(Other definitions for thews that I've seen before include "Well-developed muscles" , "Strong muscles" , "Muscle, strength (literary)" .)