Not a major issue (5)

I believe the answer is:

child

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'issue' is the definition.
(I know that child is a type of issue)

I can't explain the remainder of the clue.

(Other definitions for child that I've seen before include "Young human" , "Toddler" , "Infant" , "Juvenile" , "Immature human" .)

I've seen this clue in the Evening Standard.

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