Pest from the West: part of picture, one about Boatman (4)
I believe the answer is:
pain
'pest' is the definition.
(thesaurus)
'the west part of picture one about boatman' is the wordplay.
'the west part of' suggests taking the first letters (the letter on the western or left end of the word).
'one about boatman' becomes 'ain' (I can't explain this - if you can you should give a lot more credence to this answer).
The initial letter of 'picture' is 'p'.
'p'+'ain'='PAIN'
'from' is the link.
Can you help me to learn more?
(Other definitions for pain that I've seen before include "Sensation of hurt" , "Symptom of hurt or disorder" , "Annoying person" , "Suffering, distress" , "Hurt feeling" .)