Duck and run, catching awful mess in sewer (10)
I believe the answer is:
seamstress
'sewer' is the definition.
(someone who sews)
'duck and run catching awful mess in' is the wordplay.
'duck' becomes 'sea duck' (sea duck is a kind of duck).
'and' says to put letters next to each other.
'run catching awful' becomes 'str' (I can't explain this - if you can you should give a lot more credence to this answer).
'in' indicates putting letters inside.
'str' going inside 'mess' is 'mstress'.
'sea'+'mstress'='SEAMSTRESS'
Can you help me to learn more?
(Other definitions for seamstress that I've seen before include "Midinette" , "sewer" , "needlewoman" , "Woman who sews for a living" , "Dressmaker" .)