Give a hand (5)
I believe this is a double definition.
'give' is the first definition.
(dealing is a kind of giving)
'a hand' is the second definition.
(I know that hand can be written as deal)
(Other definitions for deal that I've seen before include "bargain > timber" , "Distribute (cards); wood" , "What business folk do" , "Timber - trade" , "Give several people a hand" .)
'give a hand?' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for slap that I've seen before include "Mild punishment" , "Cuff" , "Strike (in the face)" , "Strike with the palm" , "Blow with open hand" .)
'give a hand' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for aid that I've seen before include "grant" , "Care, assistance" , "Help or support" , "Help. Assist" , "Care and help" .)
'give a hand' is the definition.
Although both the answer and 'give' are nouns, they are not in the same form of the noun.
'give a hand' is the wordplay.
'give' becomes 'deal' (dealing is a kind of giving).
'a hand' becomes 's' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'deal'+'s'='DEALS'
Can you help me to learn more?
(Other definitions for deals that I've seen before include "Hands around the cards" , "Bargains" , "Business agreements" , "Distributes playing cards" , "Passes cards around" .)