Behold health worker going round, tuneful (7)
I believe the answer is:
melodic
'tuneful' is the definition.
(I've seen this in another clue)
'behold health worker going round' is the wordplay.
'behold' becomes 'lo' (archaic exclamation meaning 'look!').
'health worker' becomes 'medic' (I've seen this before).
'going round' means one lot of letters goes inside another (some letters go around others).
'lo' inserted into 'medic' is 'MELODIC'.
(Other definitions for melodic that I've seen before include "Of music, tuneful and sweet" , "Old mice (anag.)" , "Pleasant-sounding" , "Pleasantly musical" , "Harmonious" .)