Son briefly trying to administer oath (5,2)
I believe the answer is:
swear in
'administer oath' is the definition.
I can't tell whether this defines the answer.
'son briefly trying' is the wordplay.
'son' becomes 's' (genealogical abbreviation for son).
'briefly' means to remove the last letter.
'trying' becomes 'wearing' (both can mean stressful or demanding).
'wearing' with its final letter removed is 'wearin'.
's'+'wearin'='SWEAR IN'
'to' is the link.
Can you help me to learn more?
(Other definitions for swear in that I've seen before include "Admit to office" , "Inaugurate by oath" , "Administer official oath" , "Get into office" , "Induct into office" .)