Saint taking on new and unexciting line of work (10)
I believe the answer is:
pentameter
'work' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how one could define the other.
'saint taking on new and unexciting line of' is the wordplay.
'saint' becomes 'Peter' (St Peter).
'taking on' is an insertion indicator.
'new' becomes 'n' (common abbreviation eg NT for New Testament).
'and' means one lot of letters go next to another.
'unexciting line of' becomes 'tame' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'n'+'tame'='ntame'
'peter' placed around 'ntame' is 'PENTAMETER'.
Can you help me to learn more?
(Other definitions for pentameter that I've seen before include "Friar Laurence's usual line" , "Verse line of 20 ac feet" , "Typical Shakespearean line" , "Line of five metric feet" .)