Waves perhaps helping to conceal aid that's held up (9)
I believe the answer is:
radiation
'waves perhaps' is the definition.
(as in radioactive waves)
'helping to conceal aid that's held up' is the wordplay.
'helping' becomes 'ration' (I've seen this before).
'to conceal' indicates putting letters inside.
'that's held up' says the letters should be written in reverse.
'aid' back-to-front is 'dia'.
'ration' placed around 'dia' is 'RADIATION'.
(Other definitions for radiation that I've seen before include "Energy emitted by eg the sun" , "Transmission of energy" , "given out with mobile phones?" , "Nuclear emissions" , "Harmful waves" .)