The answers interlock.
4.ac. Immobility's associated with city transport (8) ?CST??I? - think the answer must be either ecstatic or ecstasis.
8.dn Hand bag no longer Thatcher's prime feature?(6) T?RI?T if 4 is ecstatic, S?RI?T if it's ecstasis
10.dn Asian coins American picked up? Gosh!(4) C?MY if 4 is ecstatic, S?MY if it's ecstasis. Sumy is the logical answer, but can't find an asian coin called that
The answer is 'script'. A scrip is an old name for a hand bag, purse or wallet. Thatcher's prime is of course 't'. And a script is the outline of a 'feature' (film)