Clue: Friend shortly runs single rounder after children (8)
Answer: MATRONLY
Explanation: Definition: rounder after children
 "mate"(a friend/companion) **minus ****its last letter**(shortly) + R(abbrev. for "runs" in cricket scores) + ONLY(single/solitary).
Defn: The unflattering description of one who is rounder/of heavier build after having children. Or is it the description of one who rounds up/tends to children in an institution? – but, if that were so, the clue gives no indication that the solution should be an adjective.