Forecaster to look at rainfall in the west (4)
I believe the answer is:
seer
'forecaster' is the definition.
(someone who sees the future)
'look at rainfall in the west' is the wordplay.
'look at' becomes 'see' (I've seen this in another clue).
'rainfall in the west' becomes 'r' (I can't justify this - if you can you should give a lot more credence to this answer).
'see'+'r'='SEER'
'to' acts as a link.
Can you help me to learn more?
(Other definitions for seer that I've seen before include "He forecasts" , "I envisage" , "One fortelling future" , "Person of vision" , "Fortune-teller" .)