Rosemary maybe sees a bit of bother brewing (4)
I believe the answer is:
herb
'rosemary maybe' is the definition.
(I know that Rosmarinus officinalis is a type of herb)
'a bit of bother brewing' is the wordplay.
'a bit of' indicates the answer is hidden within the clue.
'HERB' is hidden within 'bother brewing'.
'sees' acts as a link.
(Other definitions for herb that I've seen before include "Plant used for flavour" , "ingredient for recipe?" , "bay perhaps" , "Wayside plant with small red flowers" , "Thyme, for example" .)