Children, it seems, are no good to you (5)
I believe the answer is:
young
'children' is the definition.
(I've seen this in another clue)
'no good to you' is the wordplay.
'no good' becomes 'ng' (abbreviation).
'to' says to put letters next to each other (I've seen this in other clues).
'ng' put after 'you' is 'YOUNG'.
'it seems are' is the link.
I am not very happy about this link. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for young that I've seen before include "Inexperienced" , "Green" , "Not yet grown" , "interviewer of PMs on the radio" , "without experience" .)