Give priestly approval to the grade below A minus (5)
I believe the answer is:
bless
'give' is the definition.
(thesaurus)
'below a minus' is the wordplay.
'below' becomes 'b' (this could be a standard abbreviation of which I'm unaware).
'a minus' becomes 'less' (I've seen this in another clue).
'b'+'less'='BLESS'
'priestly approval to the grade' acts as a link.
I am not very happy about this link. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for bless that I've seen before include "set aside for holy purpose?" , "Make holy" , "Approve of" , "Consecrate; be thankful for" , "perform consecration" .)