Serving up potato on time, showing sign of distress (6)
I believe the answer is:
mayday
'sign of distress' is the definition.
'Mayday' can be an answer for 'sign' (Mayday is an example). I am not sure about the 'of distress' bit.
'serving up potato on time' is the wordplay.
'serving up' says the letters should be written in reverse.
'potato' becomes 'yam' (I have seen 'Sweet potato' mean 'yam' so perhaps 'potato' could also mean 'yam').
'on' says to put letters next to each other.
'time' becomes 'day' (day is a kind of time).
'yam' reversed gives 'may'.
'may'+'day'='MAYDAY'
'showing' acts as a link.
Can you help me to learn more?
(Other definitions for mayday that I've seen before include "Radio distress call" , "International radio distress signal" , "Request for help" , "call for help?" , "I'm in trouble" .)