First of girls arriving with one boy finding fortified place (8)
I believe the answer is:
garrison
'place' is the definition.
(garrisoning is a kind of placing)
'first of girls arriving with one boy' is the wordplay.
'first of' indicates taking the first letters.
'arriving' becomes 'arr' (abbreviation used in transport).
'with' means one lot of letters go next to another.
'one' becomes 'i' (Roman numeral).
'boy' becomes 'son' (male child).
The first letter of 'girls' is 'g'.
'g'+'arr'+'i'+'son'='GARRISON'
'finding fortified' 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 garrison that I've seen before include "Station (troops) in a town" , "Body of troops guarding a stronghold" , "Military stronghold" , "Troops stationed in a town or fortress" , "army base?" .)