Crossed a hill crest in the outskirts of Brentwood (7)
I believe the answer is:
bridged
'crossed a hill' is the definition.
'bridged' can be an answer for 'crossed' (bridging is a kind of crossing). I'm not sure about the 'a hill' bit.
'crest in the outskirts of brentwood' is the wordplay.
'crest' becomes 'ridge' (I've seen this before).
'in' means one lot of letters goes inside another.
'the outskirts of' says to hollow out the word (remove centre letters).
'brentwood' with its middle taken out is 'bd'.
'ridge' inserted into 'bd' is 'BRIDGED'.
Can you help me to learn more?
(Another definition for bridged that I've seen is " Spanned".)