One load delivered, attempt worship (8)
I believe the answer is:
idolatry
'worship' is the definition.
(I know that Idolatry is a type of worship)
'one load delivered attempt' is the wordplay.
'one' becomes 'a' (a thing is one thing).
'load' is an insertion indicator (some letters are loaded into others).
'delivered' becomes 'idol' (I can't explain this - if you can you should give a lot more credence to this answer).
'attempt' becomes 'try' (synonyms).
'idol'+'try'='idoltry'
'a' put into 'idoltry' is 'IDOLATRY'.
Can you help me to learn more?
(Other definitions for idolatry that I've seen before include "Adroitly (anag.)" , "Worship of carved image" , "Dilatory way of worshipping" , "Worship of a false god" , "reverence" .)