Watch bag containing American know-how (4,4)
I believe the answer is:
take note
'watch bag' is the definition.
'take note' can be an answer for 'watch' (thesaurus). I am not sure about the 'bag' bit.
'containing american know-how' is the wordplay.
'containing' indicates putting letters inside.
'american' becomes 'a' (common abbreviation - e.g. in organisation names).
'know' becomes 'ken' (I've seen this in another clue).
'how' becomes 'tote' (I can't explain this - if you can you should believe this answer much more).
'a'+'ken'='aken'
'aken' inserted inside 'tote' is 'TAKE NOTE'.
Can you help me to learn more?
(Other definitions for take note that I've seen before include "Pay attention" , "Observe closely" , "mark?" , "what the stenographer does" , "Observe and absorb - jot it down" .)