Out to produce froth (5)
I believe the answer is:
forth
'out' is the definition.
(I've seen this before)
'produce froth' is the wordplay.
'produce' indicates anagramming the letters (I've seen 'producing' mean this).
'froth' anagrammed gives 'FORTH'.
'to' acts as a link.
(Other definitions for forth that I've seen before include "Out and away -- UK shipping forecast area" , "Water" , "Scottish river and firth" , "River and estuary in eastern Scotland" , "(Go) away" .)