Clue: Insists on giving vital supplies in church — payment invested in crosses (5-5)
Answer: FORCE FEEDS
Explanation: Definition: Insists on giving vital supplies
An envelope ('invested in') of CE ('Church' of England) plus FEE ('payment') in FORDS ('crosses'). I was hoping that the church for once might be RC: it gave me the answer, even if I had to change horses in mid-stream.