Worker to speak precariously (4,2,5)
I believe the answer is:
hand to mouth
'precariously' is the definition.
(I've seen this in another clue)
'worker to speak' is the wordplay.
'worker' becomes 'hand' (hand is a kind of worker).
'speak' becomes 'mouth' (synonyms).
'hand'+'to'+'mouth'='HAND-TO-MOUTH'
(Other definitions for hand to mouth that I've seen before include "how poor people live?" , "Show of embarrassment" , "Precarious (existence)" .)