1: African region of birth (5)
2: Devil and saint share presentation (13)
3: Her rash became more severe (7)
4: Nixon-Reagan era political appointments (9)
5: Soldier shelled in song from the past (5)
6: Gulf expressed in certain letters (5)
7: Hearty policeman plugs frozen treats (3,6)
10: Liquidation of one country led by pair of fools (13)
12: A slight possibility of actor Jackie taking one's place in office (3,6)
14: Great flow dissipated into phosphorescent aura (9)
16: Witty remark, for example, about constant batterer (7)
18: Speak slowly, with upward lilt at the beginning (5)
19: Excessively sentimental dunderhead in the river (5)
20: Moderator conceals bard's inspiration (5)