Emit distress signal with little power (4)
I believe the answer is:
weep
'emit distress signal' is the definition.
(weeping might indicate someone is distressed)
'with little power' is the wordplay.
'with' is a charade indicator (letters next to each other).
'little' becomes 'wee' (similar in meaning).
'power' becomes 'p'.
'wee' next to 'p' is 'WEEP'.
(Other definitions for weep that I've seen before include "Cry, shed tears" , "Seep slowly out" , "leak" , "Express grief or sorrow" , "Turn on the waterworks" .)