Head office girl's soaring cry of adoration (7)
I believe the answer is:
hosanna
'cry of adoration' is the definition.
(I've seen this in another clue)
'head office girl's soaring' is the wordplay.
'head office' becomes 'HO'.
'girl's' becomes 'annas' ().
'soaring' is a reversal indicator (in a down clue, letters 'soar' up).
'annas' in reverse letter order is 'sanna'.
'ho'+'sanna'='HOSANNA'
(Other definitions for hosanna that I've seen before include "A cry of praise to God, from Hebrew" , "Adoring cry" , "shout in adoration" , "Said in praise of God" , "Cry of praise or joy" .)